Summi Pontificatus §72

⁷² A disposition, in fact, of the divinely sanctioned natural order divides the human race into social groups, nations or States, which are mutually independent in organization and in the direction of their internal life. But for all that, the human race is bound together by reciprocal ties, moral and juridical, into a great commonwealth directed to the good of all nations and ruled by special laws which protect its unity and promote its prosperity.